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In this paper, the performance of a two-port single-mode fiber-silicon wire waveguide coupler module which utilizes an identical spot-size converter (SSC) at the input and output ports is reported. Each of the silicon (Si)-based SSCs comprised cascaded horizontal linear and vertical nonlinear up-tapers measured 300 and 200 mum in length, respectively, in a common silicon-on-insulator (SOI) substrate. The structural parameters of the tapers were designed for compactness and relaxed tolerance to fabrication errors. The total length of the two-port coupler module was 1000 mum plus the variable length of the wire waveguide connecting the two SSCs. The mode-field diameter (MFD) of the Si-wire waveguide, 0.32 times 0.46 mum2, was transformed to the diameter of 2.8 times 8.0 mum2 at the wavelength of 1.55 mum (corresponding to an area expansion of about 150 times) and vice versa by the SSCs with a net transmission loss of 4.1 dB/port. The field-mismatch loss between the SSC and the single-mode fiber with the MFD of 5.2 mum was 2.1 dB/port.